The present invention relates to semiconductor devices and manufacturing methods thereof, and more particularly, to a solid-state imaging element including a so-called backside illuminated light receiving element, and a manufacturing method thereof.
The solid-state imaging element is a semiconductor device with an electrode, a wiring, and a light receiving element, such as a photodiode, formed over a surface of a semiconductor substrate. The solid-state imaging element normally has a so-called front-side illuminated structure that applies light for photoelectric conversion from the upper side (front-side) thereof to the light receiving element.
In the front-side illuminated light receiving element, however, the light is applied from the upper side of a metal wiring formed above the light receiving element, which causes a part of the light to be reflected by the metal wiring or the like. As a result, the light cannot effectively reach the light receiving element, which is a problem for the light receiving element. In order to solve the problem, the so-called backside illuminated solid-state imaging element has been developed which is designed to irradiate the light receiving element with light for the photoelectric conversion from the lower side (back-side) of the imaging element. For example, Japanese Unexamined Patent Publication No 2006-59873 (Patent Document 1) is disclosed in the backside illuminated solid-state imaging element.